POLYMER SHEET PATTERNING AND ITS ASSEMBLY USING SLIT CHANNEL LITHOGRAPHY
Synthesizing polymeric sheets in a slit fluidic channel by projection of a pulse of illumination to the channel. A slit channel can include a polymeric device with a plane's width larger than 1 mm. A glass plate is placed above the channel to prevent the channel from sagging. A photocurable prepolymer is flowed through the channel. The flow is paused and an illumination is projected to the channel through a photomask, produces a polymer sheet. The polymer sheet is then flushed out by resuming the flow. This process is repeated enabling continuous synthesis of polymeric sheets. The sheets can obtain any patterns defined by the photomask design, such as micropores and other geometrical patterns. These polymer sheets can be used in many emerging areas of technologies such as lab-on-a-chip, tissue engineering and organic electronics.
This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/877,496 filed Sep. 13, 2013 entitled POLYMER SHEET PATTERNING AND ITS ASSEMBLY USING SLIT CHANNEL LITHOGRAPHY, the contents of which are hereby incorporated by reference into the Detailed Description of Example Embodiments.
FIELDExamples relate to techniques for synthesizing thin polymeric sheets in a slit fluidic channel.
SUMMARYSynthesizing thin polymeric sheets in a slit fluidic channel by projection of a pulse of illumination to the channel. A slit channel can be considered a polymeric device with plane's width larger than, for example, 1 mm. A solid layer is placed above the channel to prevent the channel from sagging. A photocurable prepolymer is flowed through the channel. The flow is paused and an illumination is projected to the channel through a photomask, produces a polymer sheet. The polymer sheet is then flushed out by resuming the flow. This process is repeated enabling continuous synthesis of polymeric sheets. The sheets can obtain any patterns defined by the photomask design, such as micropores and other geometrical patterns. In the sheet thickness direction, the pattern profile can be cylindrical or conical by adjusting the focal plane to different vertical positions of the channel. The surface of the sheets can be controlled to produce smooth, porous or wrinkled texture by changing the components and their concentrations in the prepolymer solution. These polymer sheets can be used in many emerging areas of technologies such as lab-on-a-chip, tissue engineering and organic electronics.
This technique can also be used for sheet assembly. First example is magnetic assembly. In the slit channel, at least one stream in the multistream system is mixed with magnetic particles. Projection of illumination produces a polymer sheet with a magnetic strip. Multiple polymer sheets with magnetic strips can be assembled by applying a magnetic field. In this way, the patterns on each sheet can be aligned in the vertical direction as desired.
Another example is for electronic packaging. An electrical microchip is focused in the middle of the slit channel by two sheath flows and stopped at certain location along the channel length. Subsequent project of illumination on to the channel produces an electrical circuit of a shape defined by the photomask simultaneously connecting the microchip bumps to the circuit. For instance, connecting a Radio Frequency Identification (RFID) chip to an antenna makes a RFID tag.
By taking advantage of the micropatterning ability of photolithography, laminar co-flow property and flow focusing feature of microfluidic channels, the present invention may be used to not only pattern functional polymer sheets bearing geometrical and chemical anisotropy but also assemble multiple hydrogel sheets into 3D structures and perform single-step attachment of RFID dies onto a patterned antenna for RFID tag fabrication. The continuous processing capacity of SFL allows this technique to operate at a high throughput fashion, which significantly simplifies polymer sheet synthesis and assembly processes while improving its efficiency.
In accordance with an example embodiment, there is provided a method for synthesizing polymeric sheets, including: providing a slit channel having a plane's width of at least 1 mm, providing a solid layer at the channel to prevent the channel from sagging, flowing a curable prepolymer through the channel, pausing the flow of curable prepolymer responsive to illumination, and projecting a source pulse of illumination to the channel through a photomask to the paused flow of curable prepolymer to produce a polymeric sheet.
In accordance with an example embodiment, there is provided a method for synthesizing polymeric sheets, including: providing a slit channel having an aspect ratio of width to height of at least 100:1, providing a solid layer at the channel to prevent the channel from sagging, flowing a curable prepolymer through the channel, pausing the flow of curable prepolymer responsive to illumination, and projecting a source pulse of illumination to the channel through a photomask to the paused flow of curable prepolymer to produce a polymeric sheet.
In accordance with an example embodiment, there is provided a method for synthesizing thin polymeric sheets, including: providing a slit channel having an aspect ratio of width to height of at least 100:1 and a plane's width of at least 1 mm, providing a solid layer at the channel to prevent the channel from sagging, flowing a curable prepolymer through the channel, pausing the flow of curable prepolymer responsive to illumination, and projecting a source pulse of illumination to the channel through a photomask to the paused flow of curable prepolymer to produce a polymeric sheet.
In accordance with an example embodiment, there is provided a method for synthesizing polymeric designs on a substrate film, including: providing a slit channel having a plane's width of at least 1 mm; providing a solid layer at the channel to prevent the channel from sagging, introducing a substrate film into the channel, flowing a curable prepolymer responsive to illumination through the channel, pausing the flow of curable prepolymer responsive to illumination, and projecting a source pulse of illumination to the channel through a photomask and through the substrate film to the paused flow of curable prepolymer responsive to illumination, to synthesize the polymeric designs onto the substrate film, and removing the substrate film having the polymeric designs thereon from the channel.
In accordance with an example embodiment, there is provided a method for synthesizing polymeric designs on a substrate film, including: providing a slit channel having a plane's width of at least 1 mm, providing a solid layer at the channel to prevent the channel from sagging, introducing a substrate film into the channel, flowing a curable prepolymer responsive to illumination through the channel, pausing the flow of curable prepolymer responsive to illumination, and projecting a source pulse of illumination to the channel through a photomask and through the substrate film to the paused flow of curable prepolymer responsive to illumination to produce the polymeric designs onto the substrate film; and removing the substrate film having the polymeric designs thereon from the channel.
In accordance with an example embodiment, there is provided a method for synthesizing polymeric sheets including membranes, including: providing a slit channel, providing a solid layer at the channel to prevent the channel from sagging, flowing a curable prepolymer responsive to illumination through the channel, pausing the flow of curable prepolymer responsive to illumination, and projecting a source pulse of illumination to the channel through a photomask to the paused flow of curable prepolymer responsive to illumination to produce a polymeric sheet including membranes.
In accordance with an example embodiment, there is provided a method for synthesizing a radio frequency identification tag, providing a slit channel, providing a solid layer at the channel to prevent the channel from sagging, flowing an electrically conductive curable prepolymer through the channel, carrying a die using the curable prepolymer responsive to illumination through the channel, pausing the flow of the electrically conductive curable prepolymer responsive to illumination when the die is aligned with the photomask designed in an antenna pattern, and projecting a source pulse of illumination to the channel through the photomask to the paused flow of the electrically conductive curable prepolymer to form an antenna and to bond the die to the antenna, to produce a radio frequency identification tag.
In accordance with an example embodiment, there is provided a method for synthesizing polymeric sheets, including: providing a slit channel having an aspect ratio of width to height of at least 100:1, providing a solid layer at the channel to prevent the channel from sagging, flowing a curable prepolymer responsive to illumination through the channel, pausing the flow of the curable prepolymer responsive to illumination, and projecting a source pulse of illumination to the channel through a photomask to the paused flow of the curable prepolymer responsive to illumination, to product a polymeric sheet.
In accordance with an example embodiment, there is provided a system for synthesizing thin polymeric sheets, including: a slit channel having a plane's width of at least 1 mm, a solid layer at the channel to prevent the channel from sagging, a control for controlling flow of a curable prepolymer to be flowing or paused, the curable prepolymer responsive to illumination, a photomask; and a source pulse of illumination to the slit channel projected to the channel through the photomask to the paused flow of curable prepolymer, to produce a polymer sheet.
Reference will now be made, by way of example, to the accompanying drawings which show example embodiments of the present application, and in which:
Similar reference numerals may have been used in different figures to denote similar components.
DESCRIPTION OF EXAMPLE EMBODIMENTSPatterned polymer sheets are widely used in a broad range of industries, and sheets with different patterned properties play different functional roles in their applications, such as porous sheets for filtrations, electrically conductive sheets for organic electronics, [1] surface textured sheet for particles immobilization, condensation of proteins, and smart adhesives, [2-4] and hydrogel sheets for tissue engineering and stem cell differentiation control. [5] Recently, advanced applications of patterned polymer sheets have been increasingly explored in emerging lab-on-a-chip technologies, in which they serve for multifraction separation, [6] gas sensing, [7] cell trapping and analysis, [8] bioassay, [9] and bioreactors. [10] Aside from single layer sheets, which usually work as a functional component in a system, assembled sheets may be much more useful and can expand its role to work as an independent functional system. For example, assembling microchannel patterned cell-laden hydrogel sheets into 3D structures vascularizes 3D artificial tissues [11] and attaching a radio-frequency-identification (RFID) microchip to a patterned organic electrical circuit essentially forms an RFID tag used for remote communication. [12]
There are numerous methods for patterning polymer sheets, including scanning beam lithography, [13] photolithography, [14] and soft and hard mold lithography. [15] Scanning beam lithography uses a laser, electron, or ion beam to scan a selected area to form a patterned polymer sheet. This technique can generate high-resolution features with arbitrary patterns, but it is time-consuming and expensive. Photolithography is a parallel process that can create patterned polymer sheets by a one-time UV light exposure through a designed photomask onto a photoresist material. However, it is a low throughput method owing to its batch-process nature. In addition, photoresist materials commonly used in photolithography are not ideal for biomedical applications where the biocompatibility or functionalization of the sheet is critical. Soft and hard mold lithography can pattern a wide range of materials and its continuous fabrication techniques, such as embossing by “rolling molds” [16] and imprinting by step&stamp process can achieve a high throughput. [17] Mold-based lithography however, is still not a very cost-effective method for polymer sheet patterning since any change in the pattern design requires a new fabrication of the mold. Further, for all of the above-mentioned patterning methods, creating chemically anisotropic sheets needs cumbersome multi-step alignment and protection procedures, making it difficult to perform in a controllable and high-throughput fashion. More importantly, these methods fundamentally lack the ability for parts positioning and sheet assembly.
We introduce here a synthesis method for patterning polymer sheets based on stop flow lithography (SFL), which not only fabricates versatile patterned polymer sheets but also manufacture assembled sheet systems, both in a one step and high throughput fashion, overcoming many of the limitations of current techniques. SFL, which was intended for non-spherical microparticle synthesis, is a photolithographic method integrated in a microfluidic channel. In this technique, a photocurable prepolymer solution is flowed through a microfluidic channel and a UV light is projected to the channel through a photomask while the flow is stopped, synthesizing a microparticle with photomask defined shape. By taking advantage of the lubrication layer at the channel walls caused by oxygen inhibition (
Despite of the product variety of these applications, Polydimethylsiloxane (PDMS) is mainly used for the channel material primarily for its optical transparency and oxygen diffusion capacity. However, due to the weak mechanical properties of PDMS, the channels are usually at most O(100) μm in width since wider channels may suffer from a sagging problem, limiting the channels to low aspect ratios (AR, ratio of channel width to height, usually less than 20) and thus limits its production to low aspect ratio micro-scale objects. By placing a glass plate into a PDMS channel, used to prevent channel deformation, we greatly widened the channel width (AR>100) and are able to fabricate high aspect ratio polymer sheets. As illustrated in
By extending microfluidic channel dimensions, we greatly expand its application area, from current microparticle fabrication to near centimeter sheet synthesis and assembly. By taking advantage of arbitrary pattern transference and high resolution shape control intrinsic to photolithography, along with repeating process capacity, this technique can be used to readily synthesize polymer sheets with any pattern in a high throughput fashion. In addition, the laminar co-flow properties associated with microfluidics allow this technique to pattern sheets with tunable chemical anisotropy. Further, by using the fluid dynamics in a microfluidic channel, for instance particle focusing by sheath flows, this technique is able to position a micro-object in the channel and then in-situ connect it to a patterned sheet via a one step UV projection, conveniently constructing an assembled functional sheet systems in a simple slit channel. In this work, we demonstrate the versatile potential of this technique from single layer sheet patterning to multi-layer or multi-parts assembly, revealing its powerful processing ability as a tool for polymer sheet synthesis and assembly.
As shown in
Controllable textures can be synthesized onto the sheet surface by tuning the composition of the prepolymer solution. As shown in
In addition to the ability to pattern complex geometries in polymer sheets with controlled pore shape and surface morphology, by introducing multiple flow streams with different chemical properties in the slit channel, polymer sheets with anisotropic chemical properties can be synthesized. Its one step yet versatile patterning ability along with its continuous processing capacity, allowing high-throughput, makes it a powerful polymer sheet patterning tool.
The hydrogel sheet patterning and cell encapsulation capability of this technique also make it a competent tool for making hydrogel scaffolds in tissue engineering applications. In tissue engineering, scaffolds play crucial roles in providing physical and chemical cues to promote cell attachment, guiding cell differentiation and assembling into 3D tissues or organs. [28] One of the strategies for 3D tissue scaffold construction is sheet-based tissue engineering, [29] in which hydrogel sheets with or without encapsulated cells are assembled into desired 3D structures for various tissue engineering applications, for example tubular artificial tissues by rolling up the sheets or 3D tissue regeneration by stacking up multiple layers of the sheets. By taking advantage of the hydrogel sheet patterning ability and laminar co-flow properties of microfluidics, this technique will be able to incorporate cell-laden hydrogel sheets with not only designed micropatterns for formation of interconnected microchannel networks after assembly, but also multiple cell types and tailored growth factor distributions for functional tissue regeneration. With its potential in tissue engineering, we have demonstrated, as shown in
As previously mentioned elongated polymerized hydrogel sheets can be connected by overlapping edges of the subsequent sheet with the proceeding one (
A 3D scaffold was created by magnetic assembly of multiple layers of micropatterned hydrogel sheets, as seen in
In addition to the aforementioned sheet patterning and their subsequent assembly, fluid dynamics in microfluidic channel, such as flow focusing for particle positioning, with integration of the patterning ability of our technique can greatly simplify and miniaturize many multi-step sheet assembly processes in industry. We demonstrated the compatibility of our technique with electronic packaging, particularly for radio frequency identification (RFID) tag fabrication, shown in
In current RFID tags manufacturing, antennas are first fabricated through etching or screen printing and then fed into an assembly line for packaging through multi-step procedures, generally including antenna aligning, adhesive dispensing, pick-and-place die bonding, and adhesive curing. Due to the complex yet high precision antenna fabrication and die handling processes, the tag packaging contribute the most significant portion to the RFID tag manufacturing cost. [30] Although fluidic self assembly was proposed to replace the pick-and-place die positioning process, [31] it needs specifically shaped dies and corresponding shaped holes on the substrate in which the dies settle, resulting in extra manufacturing costs. In addition, the overloading of the number of the dies to increase the probability of matching and assembly requires unnecessary mass production of the dies.
By integrating the unique particle focusing feature of microfluidic channels and geometrical patterning ability of flow lithography, we are able to position micro-dies inside the channel, fabricate the antenna, and in situ attach the die to the antenna in a single step. Fabrication of RFID tags involves the attachment of bumps on the die (
Instead of prefabrication of the antenna and subsequent multistep positioning and bonding processes, this technique uses in-situ polymerization to complete the antenna fabrication and die bonding in a single step after the facile flow focused alignment, condensing the multiple steps of tag fabrication involved in current industrial practice. Moreover, owing to the development of advanced silicon integrated circuit (IC) manufacturing technologies, RFID dies are increasingly produced in smaller size, for example only 100 μm square made by Hitachi, resulting in higher packaging cost because of difficulties in precision handling. [30] Current industrial processes will need new equipments or have to upgrade their existing ones in order to adapt to these smaller silicon dies. The technique we proposed in this manuscript has great potential as it overcomes these limitations through its simple yet precise micro-object handling and arbitrary sheet patterning ability. By simplifying and miniaturizing the tag fabrication processes, this technique would greatly improve current RFID packaging efficiency while significantly reduce the cost of the tags, promoting the massive deployment of RFID tags.
We have developed a slit channel lithography method for polymer sheet patterning and assembly as well as demonstrated its versatility in potential applications. This is the first time that a near centimeter wide PDMS microfluidic channel has been developed and studied for its applications. By taking advantage of the micropatterning ability of photolithography and laminar co-flow property, we showed that this technique can pattern functional polymer sheets bearing geometrical and chemical anisotropy with controllable surface textures in a one-step fashion. With designed patterned features, we were able to readily assemble the hydrogel sheets into different 3D structures for potential application in tissue engineering. In addition, the flow focusing feature of microfluidic channel enabled us to perform single-step connection of RFID dies onto a patterned antenna for RFID tag fabrication. With its versatile while one step polymer sheet synthesis and assembly capability, we believe slit channel lithography will encourage more innovations in a wide range of applications such as membrane-based sensors, organic electronics and sheet structure assembly. Importantly, the continuous processing capacity of flow lithography allows this technique to operate at a high-throughput fashion, which significantly simplifies polymer sheet patterning and assembly processes while improves its efficiency.
Experimental Section
Slit Microfluidic Device Fabrication. Slit PDMS channels up to 8 mm wide was fabricated using soft lithography method. During the fabrication process, a glass plate was placed into the PDMS just above the channel to prevent the channel from sagging.
Photopolymerization Setup. The polymeric sheet synthesis and assembly system are based on a stop flow lithography setup. In a system configuration, a metal arc lamp was used as the UV source (Lumen 200, Prior Scientific, Rockland, Mass., USA) and a UV shutter (Lambda SC, Sutter Instruments, Novato, Calif., USA) was installed in the UV light path to control the UV exposure time. The pneumatic solution feeding system consisted of a serial connection of a pressure regulator (Type 100LR, ControlAir, Amherst, N.H. USA) to a three-way solenoid valve (Model 6014, Burkert, Germany) and at the end, to the PDMS channel. The UV shutter and the solenoid valve were both controlled by a program in Labview (National Instruments, Austin, Tex., USA) through a digital controller (NI 9472, National Instruments, Austin, Tex., USA) to coordinate the synthesis process of flow-stop, UV exposure (synthesis) and flow-resume, in a repeating pace. An inverted microscope Axio Observer (Carl Zeiss, Jena, Germany) equipped with objectives of 5×/0.13, 10×/0.3 and 20×/0.4 (N-Achroplan, Ec plan-Neofluar and korr LD Plan-Neofluar, Carl Zeiss, Jena, Germany) was used for this study. A UV filter set (11000v3, Chroma, VT, USA) was used to filter the UV light source to obtain desired UV excitation for polymerization. The red and green filters (XF101-2, XF100-2 Omegafilters, VT, USA) were used for the fluorescence imaging. The transparency photomasks were designed with AUTOCAD 2011 and printed at a resolution of 25,000 dpi (CAD/Art Services, OR, USA).
Single Layer Sheet Synthesis. In single layer sheet synthesis, channels with depth of 50 μm were used. Geometrically patterned sheets in
Cell-laden sheets and hydrogel sheets assembly. 2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959, Sigma-Aldrich) was used as photoinitiator and dissolved in the mixture of PEG-DA 700 and phosphate buffered saline (PBS). The prepolymer solution without cells was a mixture of 20% (v/v) PEG-DA 700, 3% (w/v) Irgacure 2959, and 80% (v/v) PBS. 3T3 fibroblasts (ATCC, Manassas, Va., USA) containing prepolymer solution was a mixture of 20% (v/v) PEG-DA 700, 3% (w/v) Irgacure 2959, and 80% (v/v) PBS with cell density of 5×106 cells mL-1.
The prepolymer solutions with and without cells were flowed into the channel to form the middle and side streams, respectively. The co-flow streams were polymerized by UV light exposure through a rectangular photomask (
Elongated hydrogel sheet (
To make the magnetic hydrogel, a prepolymer solution containing 10% (v/v) magnetic beads solution (1 μm, Sera-Mag, Thermo Scientific, Canada), 40% (v/v) PEG-DA 700, 50% (v/v) DI water and 6% (w/v) Irgacure 2959 was used as the side streams and non-magnetic prepolymer solution containing 40% (v/v) PEG-DA 700, 60% (v/v) DI water and 5% (w/v) Irgacure 2959 was used as the middle stream (
RFID tag fabrication. RFID dies were obtained from Alien Technology (Morgan Hill, Calif., USA). 2 mg/mL CNT prepolymer solution was obtained by dispersing CNT (Cheaptubes, Brattleboro, Vt., USA) in PEG-DA 700 (40%) and DI water (60%) solution. The die was placed in the middle inlet reservoir. CNT prepolymer solution was passed through the two inlets, forming three streams. The flow rate of the two side streams were controlled at 3 μL s-1 and middle one was controlled at 1 μL s-1. The dies were focused into the middle of the channel and were stopped at a downstream location by pausing the flows (
Slit Microfluidic Device Fabrication. An example embodiment of the slit microfluidic device system 600 is shown in
Surface Textured Sheets. With reference to
Cell-laden sheets and hydrogel sheets assembly.
Cellular prepolymer solution preparation. 3T3 fibroblasts (ATCC, Manassas, Va., USA) were grown in Dulbecco's Modified Eagle's medium (DMEM) (Sigma-Aldrich, St. Louis, Mo., USA) supplemented with 10% fetal bovine serum (FBS) and 1% antibiotic. The cells were then incubated at 37° C. in a humidified atmosphere of 95% air and 5% CO2. The cell containing prepolymer solution was a mixture of 20% (v/v) PEG-DA 700, 3% (w/v) Irgacure 2959, and 80% (v/v) PBS with cell density of 5×106 cells mL-1. Before mixing with cells, the prepolymer solution was filter-sterilized through a 0.22 μm filter.
Elongated hydrogel sheet. With reference to
Reference is now made to
Reference is now made to
In accordance with some example embodiments which include the channel, in addition to glass, any solid material known by those skilled in the art, such as metal, alloy, plastic and ice, can also be used to support the channel, to prevent it from deformation. In accordance with some example embodiments of the channel, in addition to PDMS, any other suitable materials known by those skilled in the art which can allow the diffusion of oxygen can also be used as the channel material.
In accordance with some example embodiments which include the photomask, the photomask can be any suitable photomask known by those skilled in the art that enables the projection and direction of illumination towards the curable prepolymer.
In accordance with some example embodiments which include the prepolymer materials, photocurable materials including materials can be cured by UV, visible light and IR. In addition to photocurable materials, thermalcurable, PH sensitive materials any other suitable materials known by those skilled in the art, can also be used. In such applications, the source of illumination is a thermal source or other source of radiation.
In accordance with some example embodiments which include the prepolymer materials, the prepolymer stream in the channel comprises a monomer or a monomer stream. The monomer stream can include a biological material such as DNA, RNA, antigen, polypeptide, antibody, enzyme, cells, mitochondria, chromophore, and virus. The monomer stream can include a porogen for making porous sheets. The monomer stream can include particles, such as carbon nanotube, graphene, magnetic particles, quantum dots, electrically conductive particles, glass particles and gas bubbles.
In accordance with some example embodiments, different antibodies can be incorporated into different location in a sheet material for multiplex cell, virus, and biomolecule detection.
In accordance with some example embodiments, CNT/graphene loaded sheets for polymer electrolyte membrane (PEM) in fuel cell, for capacitor in energy storage/battery.
In accordance with some example embodiments, by incorporating magnetic particles into the sheets, 3D laminate structures can be obtained through field assisted self-assembly.
In accordance with some example embodiments, the flow focusing and subsequent in-situ polymerization can also be used for assembling a LED or other micro-component to a planar structure.
While particular embodiments of the invention have been shown and described in detail, it will be obvious to those skilled in the art that changes and modifications of the present invention, in its various embodiments, may be made without departing from the spirit and scope of the invention. Other elements, steps, methods and techniques that are insubstantially different from those described herein are also within the scope of the invention. Thus, the scope of the invention should not be limited by the particular embodiments described herein but should be defined by the appended claims and equivalents thereof.
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Claims
1. A method for synthesizing polymeric sheets, comprising:
- providing a substrate which defines a slit channel having a plane's width of at least 1 mm;
- providing a solid layer at the slit channel to prevent the slit channel from sagging;
- flowing a curable prepolymer responsive to illumination through the slit channel;
- pausing the flow of the curable prepolymer responsive to illumination; and
- projecting a source pulse of illumination to the slit channel through a photomask to the paused flow of the curable prepolymer responsive to illumination, to produce a polymeric sheet.
2. The method of claim 1, wherein the slit channel has an aspect ratio of width to height of at least 100:1.
3. The method of claim 1, further comprising resuming flow and flushing the polymeric sheet.
4. The method of claim 1, wherein the photomask includes a specified design.
5. The method of claim 4, wherein the specified design includes at least one of micropores and geometrical patterns.
6. The method of claim 1, further comprising applying the method to one of a lab-on-a-chip, an RFID circuit, tissue engineering, organic electronics, and to generate a filtration membrane.
7. The method of claim 1, further comprising repeating the flowing, the pausing and the projecting to a stream of the curable prepolymer.
8. The method of claim 7, further comprising overlapping a trailing edge of a synthesized first polymeric sheet onto a leading edge of a subsequently synthesized second polymeric sheet to produce an elongated polymeric sheet formed from the overlapped first and second polymeric sheets.
9. The method of claim 1, further carrying a micro-object using the curable prepolymer responsive to illumination through the channel; and
- pausing the flow of the curable prepolymer responsive to illumination when the micro-object is aligned with the photomask.
10. The method of claim 9 wherein the curable prepolymer is an electrically conductive prepolymer solution, the micro-object is a die and the photomask is designed in an antenna pattern, and wherein the projecting the source pulse of illumination to the slit channel through the photomask forms an antenna and bonds the die to the antenna forming an electrical circuit.
11. The method of claim 1, wherein the substrate is defined by a layer including Polydimethylsiloxane (PDMS).
12. The method of claim 1, wherein the slit channel is supported by the solid layer, the solid layer including at least one of glass, metal, alloy, plastic and ice.
13. The method of claim 12 wherein the solid layer is dimensioned slightly larger than the slit channel.
14. The method of claim 1, wherein the slit channel is defined by a layer of a suitable material which allows diffusion of oxygen.
15. The method of claim 1, wherein the plane's width is about 8 mm.
16. The method of claim 1, wherein the curable prepolymer includes a photocurable prepolymer that can be cured by ultraviolet (UV), visible light or infrared (IR), or a thermalcurable prepolymer.
17. The method of claim 1, wherein the curable prepolymer in the slit channel comprises a monomer.
18. The method of claim 17, wherein the monomer includes a biological material including at least one of a DNA, RNA, antigen, polypeptide, antibody, enzyme, cells, mitochondria, chromophore, and virus, or a porogen for making porous sheets.
19. The method of claim 17 wherein the monomer includes a water soluble solution.
20. The method of claim 17, wherein the monomer includes particles, including at least one of carbon nanotube, graphene, magnetic particles, quantum dots, electrically conductive particles, glass particles and gas bubbles.
21. The method of claim 1, wherein different antibodies are incorporated into different location in a sheet material for at least one of multiplex cell, virus, and biomolecule detection.
22. The method of claim 1, wherein patterned conductive sheets are synthesized for at least one of sensing circuits and organic electronics.
23. The method of claim 1, wherein carbon nanotube (CNT) or graphene loaded sheets are synthesized for polymer electrolyte membrane (PEM) in a fuel cell, or for a capacitor in energy storage or battery.
24. The method of claim 1, further comprising incorporating magnetic particles into the polymeric sheet.
25. The method of claim 1, wherein flow focusing and subsequent in-situ polymerization can also be used for assembling a LED or other micro-component to a planar structure.
26. The method of claim 1 further comprising adjusting the focal plane to different vertical positions of the slit channel to form cylindrical or conical pore profiles.
27. The method of claim 1 wherein the polymeric sheets have a width of at least 1 mm.
28. A method for synthesizing a polymeric sheet including membranes, comprising:
- providing a substrate defining a slit channel;
- providing a solid layer at the slit channel to prevent the slit channel from sagging;
- flowing a curable prepolymer responsive to illumination through the slit channel;
- pausing the flow of curable prepolymer responsive to illumination; and
- projecting a source pulse of illumination to the slit channel through a photomask to the paused flow of curable prepolymer responsive to illumination, to produce the polymeric sheet including membranes.
29. A method for synthesizing a radio frequency identification tag, comprising:
- providing a substrate defining a slit channel,
- providing a solid layer at the slit channel to prevent the slit channel from sagging,
- flowing an electrically conductive curable prepolymer through the slit channel,
- carrying a die using the electrically conductive curable prepolymer responsive to illumination through the slit channel,
- pausing the flow of the electrically conductive curable prepolymer responsive to illumination when the die is aligned with the photomask designed in an antenna pattern,
- and projecting a source pulse of illumination to the slit channel through the photomask to the paused flow of the electrically conductive curable prepolymer to form an antenna and to bond the die to the antenna, to produce the radio frequency identification tag.
30. The method of claim 29 further comprising:
- positioning the die in the slit channel by flowing a stream of the electrically conductive curable prepolymer into the slit channel along each side of the die.
31. The method of claim 29 wherein the slit channel is dimensioned to align the die with the photomask.
32. The method of claim 29 further comprising:
- positioning the die carried by the electrically conductive curable prepolymer in the slit channel using a magnetic force.
33. A system for synthesizing a polymeric sheet, comprising:
- a substrate defining a slit channel having a plane's width of at least 1 mm;
- a solid layer at the slit channel to prevent the channel from sagging;
- a control configured for controlling flow of a curable prepolymer to be flowing or paused, the curable prepolymer responsive to illumination;
- a photomask; and
- a source pulse of illumination to the slit channel projected to the channel through the photomask to the paused flow of curable prepolymer, to produce the polymeric sheet.
34. The system of claim 33 wherein the slit channel has an aspect ratio of width to height of at least 100:1.
35. The system of claim 33 where the solid layer includes at least one of glass, metal, alloy, plastic and ice.
Type: Application
Filed: Sep 12, 2014
Publication Date: Mar 19, 2015
Inventors: Minggan LI (Oakville), Dae Kun HWANG (Toronto), Janusz KOZINSKI (Toronto)
Application Number: 14/484,950
International Classification: G03F 7/20 (20060101);